Conventional combines, either self propelled or pulled by a tractor, harvest grain and load the grain into a tank. Either the combine is emptied when the tank is full, or a truck moves next to the combine and the grain is unloaded from the combine onto the truck using a load-out tube. The moisture content of the grain coming out of the field is high, often on the order of 18 to 30%. Eventually the unloaded grain is stored by heating it to eliminate excess moisture and cooling it just before storage, the moisture content typically being reduced to around 16% for storage. Ultimately the moisture content before the grain is sold and shipped should be around 14 to 15%.
There have been a number of proposals in the past for effecting drying of the grain right on the combine. These proposals use various mechanisms to effect heating of the grain so as to reduce the moisture content, often using a source of waste heat from the combine internal combustion engine and/or another source of heat. However the prior proposed structures have apparently not been commercially successful, perhaps because they do not carefully enough simulate the drying action that is conventionally practiced, and thereby do not necessarily eliminate subsequent off-vehicle drying steps.
According to the present invention, a combine is provided which effectively treats the grain harvested thereby so that it is properly dried and then cooled before the grain is discharged from the combine into a trailing truck or the like. The combine according to the invention closely simulates conventional grain drying techniques yet accomplishes them on the combine itself, and allows for grain drying and cooling in a cost effective manner.
According to one aspect of the present invention, the drying means associated with the combine comprise first, second and third distinct chambers interconnected by conveyors, such as augers. A fan, or like device, is associated with each of the chambers for circulating air through the chamber to remove moisture from grain disposed within the chamber. A common fan may be provided for circulating air through all of the chambers. The circulating air in the first two chambers picks up heat since those chambers are heated, while the air in the third chamber is either ambient or cooled air which merely removes heat from the grain--along with associated moisture--and rejects it into the atmosphere.
The first chamber of the combine according to the invention includes one or more perforated walls which have heat exchanger tubes associated with them, the heat exchanger tubes being either connected up to the radiator of the combine engine, or to the exhaust gas manifold. In the second chamber, a hollow body is provided within the chamber. The hollow body includes a burner for hydrocarbon fuel, such as diesel or propane. In the third chamber, the air passes through the perforated walls at the bottom and picks up moisture as it moves to a vent at the top, no heat being added. From the third chamber the grain is discharged by a load out auger tube or the like.
It is the primary object of the present invention to provide effective on-vehicle drying of grain harvested by a combine. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.